Dogs are also the only other animals that can prostatic hypertrophy. Make sure it is not a prostate Ca, they can treat it with hormonal.
I am not a Vet, but if it is transitional cell cancer and superficial only then intra bladder chemo may be effective just like in humans. If invasive then most animals get surgery (mainly due to lack of radiation facilities for animals, but they do exist) If you can and once again, just like humans , you can try bladder sparing approaches. This will be more expensive, but just like humans, if it works the pet will be more functional.